A couple hundred people attended the service Saturday afternoon at South Coast Botanic Garden -- many of the guests were musicians who'd played or toured with Chester and Linkin Park. A full stage, including a drum kit, was set up for musical tributes to be performed.

Police provided tight security at the event. As TMZ first reported ... the family opted for a private funeral, instead of a massive open service. Instead, fans have organized numerous memorials around the globe for the frontman, who hanged himself just over a week ago.

Fittingly, all funeral attendees had to have wrist bands and an access pass -- similar to most concert VIP passes.

Chester was 41. #RIP